Drug delivery refers to the method, formulation and technology for carrying a pharmaceutical compound to a specific site of action in the body. A drug delivery system can consist of a drug working in combination with a medical device, or it could only be a chemical formulation of a drug.
Different methods of drug administration have been designed to supplement the large number of new drugs being produced and to support those that can't be delivered by oral ingestion or injection. Oral drug administration is not always highly reliable due to a tendency to have negligible or very little absorption due to enzymatic degradation in the gastrointestinal tract and liver. Also, for example in the case of Aspirin if taken orally, in high doses, it causes gastrointestinal ulcers. The routes of pharmaceutical delivery are usually determined by the disease that needs to be treated and the kind of effect the drug needs to have and a drug is usually administered systemically or directly to the target site.
One particular method of applying a drug to a patient that has shown much promise, is using a transdermal patch. This allows the drug to pass through or into the skin for a variety of potential treatments. However, often it is difficult for the majority of a drug to pass through the skin at therapeutically useful rates thus far. This is due to the outer stratum corneum layer of the skin acting as a natural barrier to external infiltration so making transdermal drug delivery very limited.
Particularly difficult conditions to treat are skin conditions such as eczema and psoriasis. The real cause of psoriasis still not fully understood; however there are two ideas about how this disorder develops. The first hypothesis indicates that Psoriasis is an immune-mediated disorder in which affecting the excessive reproduction of the skin cells. The second hypothesis indicates that Psoriasis is due to dysfunction of the epidermis and keratinocytes, which is, then cause to excessive growth and reproduction of the skin cells.
Symptoms of Psoriasis differ from one type to other, but the general symptoms would be inflammation, erythema (redness), thickness, heat and scaling. Patient suffering Psoriasis reported that they have significant feeling of self-consciousness and embarrassment and they usually avoided social activities and limited dating or friendly interactions.
Currently there are no absolute cures for this disease; however there are different treatments methods, which could help to control the symptoms such as using topical creams, gels and ointment formulations relieve the inflammation and slow down the reproduction of the skin cells. The problem with these methods is they could spread on the healthy part of the skin, dying them, due to the yellow colour of drug and cause irritation. The dose also cannot be consistent per cm2 due to applying inconsistently by patients.
Accordingly, there is a continued interest therefore in the development of new topical compositions that could efficiently treat a subject suffering from the above condition.
The present invention seeks to overcome problems associated with the prior art by providing a delivery system that can be applied to the skin and which releases drugs to the skin at a therapeutically acceptable level. The drug delivery device of the invention is particularly useful for treating long term debilitating skin diseases such as eczema and psoriasis where targeted delivery is required over a period of time, while avoiding irritating the skin or causing the disease to spread further.